1 Expert Answer

Article usually means an elaborate write up gathering data from mutliple perspectives or experiments. It also includes the relevant references from the field of study, data displayed as histograms, graphs, pictures etc. Usually articles are on the burning problems and hot topics.

Perspective is a short journal article that deals with unique and new perspective of a common problem. Since I am scientist, I shall give you a scientific example. The journal Nature publishes a research article submitted by authors with real experiments and results on Parkinson's disease. The journal invites the leaders in Parkinson's field to write a brief article on original research article and past work in the field as a perspective. This short perspective article would include that how latest research in the article changes the thought process in the field adding a new perspective.

Letter in Nature is a short scientific article that only includes a particular aspect of scientific problem. It is essentially a smaller version of full research article.

Review is a much larger than all these write up that I mention above, usually it does not include new research but it includes extensive literature search and provides concise information to readers on the topic for all different kind of research studies/case studies and reported data for subjects like political science and social science.

I hope this helps, please let me know if you have additional question. I shall be happy to explain.